view hgext3rd/topic/destination.py @ 5601:3946ee4ee3ae

topic: add a `exp….topic.linear-merge` option to allow some oedipus

If this option is set to `from-branch`, a user can call `hg merge some-topic`
from a bare branch even if `some-topic` is a direct descendant of the current
working copy parents. This was previously denied if the changesets was on the
same branch, since the result would be an "oedipus merge".

Some user have been requesting this, and this type of merge is one of Gitlab
standard way of merging a "Merge Request". That new option will unlock issue
`heptapod#200` and make this mode available for those who wants it.

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    bookmarks,
    destutil,
    error,
    extensions,
)
from . import (
    common,
    topicmap,
    constants,
)
from .evolvebits import builddependencies

def _destmergebranch(orig, repo, action=b'merge', sourceset=None,
                     onheadcheck=True, destspace=None):
    # XXX: take destspace into account
    if sourceset is None:
        p1 = repo[b'.']
    else:
        # XXX: using only the max here is flacky. That code should eventually
        # be updated to take care of the whole sourceset.
        p1 = repo[max(sourceset)]
    top = None
    if common.hastopicext(repo):
        top = p1.topic()
    if top:
        revs = repo.revs(b'topic(%s) - obsolete()', top)
        deps, rdeps = builddependencies(repo, revs)
        heads = [r for r in revs if not rdeps[r]]
        if onheadcheck and p1.rev() not in heads:
            raise error.Abort(_(b"not at topic head, update or explicit"))

        # prune heads above the source
        otherheads = set(heads)
        pool = set([p1.rev()])
        while pool:
            current = pool.pop()
            otherheads.discard(current)
            pool.update(rdeps[current])
        if not otherheads:
            # nothing to do at the topic level
            bhead = ngtip(repo, p1.branch(), all=True)
            if not bhead:
                raise error.NoMergeDestAbort(_(b"nothing to merge"))
            elif 1 == len(bhead):
                return bhead[0]
            else:
                msg = _(b"branch '%s' has %d heads "
                        b"- please merge with an explicit rev")
                hint = _(b"run 'hg heads .' to see heads")
                raise error.ManyMergeDestAbort(msg % (p1.branch(), len(bhead)),
                                               hint=hint)
        elif len(otherheads) == 1:
            return otherheads.pop()
        else:
            msg = _(b"topic '%s' has %d heads "
                    b"- please merge with an explicit rev") % (top, len(heads))
            raise error.ManyMergeDestAbort(msg)
    return orig(repo, action, sourceset, onheadcheck, destspace=destspace)

def _destupdatetopic(repo, clean, check=None):
    """decide on an update destination from current topic"""
    if not common.hastopicext(repo):
        return None, None, None
    movemark = node = None
    topic = repo.currenttopic
    if topic:
        revs = repo.revs(b'.::topic(%s)', topic)
    elif constants.extrakey in repo[b'.'].extra():
        revs = []
    else:
        return None, None, None
    if revs:
        node = revs.last()
    else:
        node = repo[b'.'].node()
    if bookmarks.isactivewdirparent(repo):
        movemark = repo[b'.'].node()
    return node, movemark, None

def desthistedit(orig, ui, repo):
    if not common.hastopicext(repo):
        return None
    if not (ui.config(b'histedit', b'defaultrev', None) is None
            and repo.currenttopic):
        return orig(ui, repo)
    revs = repo.revs(b'::. and stack()')
    if revs:
        return revs.min()
    return None

def ngtip(repo, branch, all=False):
    """tip new generation"""
    ## search for untopiced heads of branch
    # could be heads((::branch(x) - topic()))
    # but that is expensive
    #
    # we should write plain code instead

    tmap = topicmap.gettopicrepo(repo).branchmap()
    if branch not in tmap:
        return []
    elif all:
        return tmap.branchheads(branch)
    else:
        return [tmap.branchtip(branch)]

def modsetup(ui):
    """run a uisetup time to install all destinations wrapping"""
    extensions.wrapfunction(destutil, '_destmergebranch', _destmergebranch)
    bridx = destutil.destupdatesteps.index(b'branch')
    destutil.destupdatesteps.insert(bridx, b'topic')
    destutil.destupdatestepmap[b'topic'] = _destupdatetopic
    extensions.wrapfunction(destutil, 'desthistedit', desthistedit)